bool a = !true
bool b = a
var b1 =!a
print(a, b, b1, '\n') // falsefalsetrue

var str = 'hello world'
bool c = !(str as bool)

string str2 = ''
bool d = !(str2 as bool)
print(c, d, '\n') // falsefalse

bool e = (1 + 1) as bool
bool f = !(3.1415926 as bool)
print(e, f, '\n') // truefalse

fn sum(int a, int b):int {
    return a + b
}
var (g, err) = try sum(12, -1)
bool h = err.has
bool i = !err.has
print(g, h, i, '\n') // 11falsetrue